Solvent extraction system for plutonium colloids and other oxide nano-particles

Abstract

The invention provides a method for extracting plutonium from spent nuclear fuel, the method comprising supplying plutonium in a first aqueous phase; contacting the plutonium aqueous phase with a mixture of a dielectric and a moiety having a first acidity so as to allow the plutonium to substantially extract into the mixture; and contacting the extracted plutonium with second a aqueous phase, wherein the second aqueous phase has a second acidity higher than the first acidity, so as to allow the extracted plutonium to extract into the second aqueous phase. The invented method facilitates isolation of plutonium polymer without the formation of crud or unwanted emulsions.

The embodiment of the invention in which an exclusive property or privilege is claimed is defined as follows: 
     
       1. A method for extracting plutonium from spent nuclear fuel, the method comprising:
 a. supplying plutonium in a first aqueous phase; 
 b. mixing the plutonium first aqueous phase with a mixture of a polar organic compound and a moiety creating a first organic mixture having a first acidity as to allow the plutonium to substantially extract into the first organic mixture; and c. mixing the extracted plutonium with a second aqueous phase, wherein the second aqueous phase has a second acidity higher than the first acidity, so as to allow the extracted plutonium to extract into the second aqueous phase; 
 d. selecting the polar organic compound as a molecule selected from the group consisting of n-octanol, hexanol, butanol, and combinations thereof, and wherein the moiety is a halocarboxylic acid. 
 
     
     
       2. The method as recited in  claim 1  wherein the halocarboxylic acid is selected from the group consisting of monochloroacetic acid, dichloroacetic acid, trichloroacidic acid, and combinations thereof. 
     
     
       3. The method as recited in  claim 1  wherein the second aqueous phase contains a moiety selected form the group consisting sulfate, carbonate, phosphate, iodate, and combinations thereof. 
     
     
       4. The method as recited in  claim 1  wherein the method is carried out at ambient temperature and pressure. 
     
     
       5. The method as recited in  claim 1  wherein no external heat is added. 
     
     
       6. The method as recited in  claim 1  wherein the plutonium is colloidal plutonium and wherein the extraction of the plutonium into the second aqueous phase is indicated by a transfer of color from the first organic mixture to the second aqueous phase. 
     
     
       7. The method as recited in  claim 1  wherein the plutonium is plutonium polymer having the formula PuO 2 . 
     
     
       8. The method as recited in  claim 1  wherein a pH of the first organic mixture ranges from between approximately −1 and 3. 
     
     
       9. A method for extracting plutonium from an aqueous solution containing plutonium, the method comprising:
 a. mixing the aqueous solution with an organic liquor containing n-octanol and trichloroacetic acid for a time sufficient to cause the plutonium to move to the organic liquor; and 
 b. mixing the organic liquor with an aqueous liquor containing sulfate moiety for a time sufficient to cause the plutonium to move into the aqueous liquor. 
 
     
     
       10. The method as recited in  claim 9  wherein the aqueous solution contains nitric acid. 
     
     
       11. The method as recited in  claim 9  wherein no external heat is added. 
     
     
       12. The method as recited in  claim 9  wherein no external pressure is added. 
     
     
       13. The method as recited in  claim 9  wherein the sulfate is present in a concentration of from about 0.025 to 2.5 M. 
     
     
       14. The method as recited in  claim 9  wherein the plutonium is present up to about 0.100 M in aqueous solution. 
     
     
       15. The method as recited in  claim 9  wherein the nitric acid is present at a concentration of between about 0.001 M and 10 M. 
     
     
       16. The method as recited in  claim 9  wherein the aqueous solution is at a pH of between approximately −1 to 3.